Gadolinium
For computer memory.
Atomic Number: 64
Atomic Symbol: Gd
Atomic Weight: 157.25
Electron Configuration:[Xe]6s^2 4f^7 5d^1History
From gadolinite, a mineral named for Gadolin, a Finnish chemist. The rare earth metal is
obtained from the mineral gadolinite. Gadolinia, the oxide of gadolinium, was separated by
Marignac in 1880 and Lecoq de Boisbaudran independently isolated it from Mosander's yttria in
1886.
Sources
Gadolinium is found in several other minerals, including monazite and bastnasite, both of which
are commercially important. With the development of ion-exchange and solvent extraction
techniques, the availability and prices of gadolinium and the other rare-earth metals have
greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with
metallic calcium.
Isotopes
Natural gadolinium is a mixture of seven isotopes, but 17 isotopes of gadolinium are now
recognized. Although two of these, 155Gd and 157Gd, have excellent capture characteristics,
they are only present naturally in low concentrations. As a result, gadolinium has a very fast
burnout rate and has limited use as a nuclear control rod material.
Properties
As with other related rare-earth metals, gadolinium is silvery white, has a metallic luster, and is
malleable and ductile. At room temperature, gadolinium crystallizes in the hexagonal,
close-packed alpha form. Upon heating to 1235oC, alpha gadolinium transforms into the beta
form, which has a body-centered cubic structure.
The metal is relatively stable in dry air, but tarnishes in moist air and forms a losely adhering
Gadolinium